Cross-linked Gelatin Research Articles

Biocompatible Hemostatic Sponge Exhibiting Broad-Spectrum Antibacterial Activity.

Hemorrhage during accidents or surgery is a significant challenge that can contribute to mortality. This is further aggravated due to bacterial infections at the injured site. Therefore, rapid application of a hemostatic and antibacterial material is highly necessary as a pretreatment for patients' survival. Herein, we have developed a hemostatic sponge (Hemobac) through amide crosslinking of gelatin and an N-(2-hydroxy) propyl-3-trimethylammonium chitosan (HTCC)-silver chloride nanocomposite (QAm1-Ag0.1) to mitigate bacterial infections, while aiding hemostasis. This Hemobac sponge completely eradicated (∼4-5 log) a wide range of Gram-positive and Gram-negative bacteria encompassing various clinical isolates within 6 h. The antihemorrhagic ability of Hemobac was ascertained through SEM images, which exhibited the presence of agglomerated blood cells onto the sponge with a significantly low blood-clotting index value (∼23 ± 1). Notably, Hemobac reduced the blood loss by ∼70-80% in the liver puncture model and femoral vein injury model in mice, displaying its improved hemostatic ability over a marketed gelatin-based sponge. Negligible hemolytic activity (∼6%) and retained healthy morphology of mammalian cells were observed upon exposure to the Hemobac sponge. Minimal immune response was noticed at the Hemobac-treated wound in mice through histopathology analysis. Collectively, these findings indicate that this biocompatible Hemobac sponge can stop the bleeding instantaneously and combat bacterial infections.

Facile Construction of Gelatin/Polyacrylamide Acrylic Acid/Sodium Alginate-Based Triple-Network Composite Hydrogels with Excellent Mechanical Performances

Three-network hydrogels have a wide range of applications due to their different network structures and diverse cross-linking methods. In this work, a triple-network hydrogel strategy based on double network coordination and cross-linking is proposed, including gelatin (Gelatin) network, polyacrylamide acrylic acid (PAMAAc) network, and sodium alginate (SA) network. SA and AAc molecular chains contain a large amount of -COO-, which can coordinate with metal ions and generate a large number of dynamic coordination bonds. The hydrogel forms the PAMAAc network through free radical polymerization, and at the same time the interpenetrating cross-linked Gelatin network and SA network are formed through hydrogen bonding. In addition, the addition of metal ions realizes the coordination cross-linking of the double network in the hydrogel. Moreover, the prepared composite hydrogels exhibit good mechanical properties and self-recovery properties. It should be noted that the concentration of different metal ions and the time of coordination and crosslinking will affect the mechanical properties of the hydrogel. The current work provides an idea for preparing a three-network hydrogel with high compressive strength and fast self-recovery.

Preparation and research of gelatine hydrogel anti-bedsore materials properties

The formation of the hydrogel polymer matrix duringthe gelatin cross-linking with dioxirane derivatives of polyoxyethylene glycolswere studied.The optimal conditions for their synthesis were determined. The characteristics of the hydrogel (swelling in different media, mechanical properties at different temperatures) were obtained depending on the type of dioxirane derivative and prepolymer ratio. The possibility of introducing several drugs into hydrogels was established and the release of these drugs was found to be prolonged.

Engineering and Evaluation of Forcespun Gelatin Nanofibers as an Isorhamnetin Glycosides Delivery System.

Opuntia ficus-indica (L.) Mill (OFI) is considered a natural source of bioactive phytochemicals, mainly isorhamnetin glycosides (IRGs). These compounds have demonstrated antioxidant, anti-inflammatory, and anticancer activities, among others. The development of a suitable delivery system for these compounds is needed to improve their chemical and biological stability. This study aimed to evaluate the feasibility of fabrication and characterization of IRG-loaded gelatin (GL) forcespun fibers and crosslinking with glutaraldehyde (GTA). Two different percentages (25% and 30% w/v) of GL were evaluated with 12% (w/v) OFI flour to obtain nanofibers GL/OFI1 and GL/OFI2, respectively. The morphology and physicochemical properties of the fibers were investigated. The results indicated that the diameters of the fibers were on the nanoscale. The amount of IRGs was determined using high-performance liquid chromatography (HPLC). The IRGs release and the cytocompatibility of the nanofibers were also evaluated. GL concentration significantly affected the IRG release. Among both nanofibers, the GL/OFI2 nanofiber achieved a cumulative IRGs release of 63% after 72 h. Both fibers were shown to be biocompatible with human skin/fibroblast cells. Specifically, GL/OFI1 nanofibers exhibited favorable features for their application as an extract-coupled release system. The IRGs-embedded GL nanofiber mats may become a good alternative for the delivery of phytochemicals for the health sector and biomedical applications.

Robust gelatin hydrogels for local sustained release of bupivacaine following spinal surgery

Adequate treatment of pain arising from spinal surgery is a major clinical challenge. Opioids are the mainstay of current treatment methods, but the frequency and severity of their side effects display a clear need for opioid-free analgesia. Local anesthetics have been encapsulated into sustained-release drug delivery systems to provide postoperative pain relief. However, these formulations are limited by rapid diffusion out of the surgical site. To overcome this limitation, we synthesized ring-shaped hydrogels incorporating bupivacaine, designed to be co-implanted with pedicle screws during spinal surgery. Hydrogels were prepared by riboflavin-mediated crosslinking of gelatin functionalized with tyramine moieties. Additionally, oxidized β-cyclodextrin was introduced into the hydrogel formulation to form dynamic bonds with tyramine functionalities, which enables self-healing behavior and resistance to shear. Feasibility of hydrogel implantation combined with pedicle screws was qualitatively assessed in cadaveric sheep as a model for instrumented spinal surgery. The in-situ crystallization of bupivacaine within the hydrogel matrix provided a moderate burst decrease and sustained release that exceeded 72 hours in vitro. The use of bupivacaine crystals decreased drug-induced cytotoxicity in vitro compared to bupivacaine HCl. Thus, the presented robust hydrogel formulation provides promising properties to enable the stationary release of non-opioid analgesics following spinal surgery. Statement of significanceCurrently, postoperative pain following spinal surgery is mainly treated with opioids. However, the use of opioids is associated with several side effects including addiction. Here we developed robust and cytocompatible gelatin hydrogels, prepared via riboflavin-mediated photocrosslinking, that can withstand orthopedic implantation. The implantability was confirmed in cadaveric instrumented spinal surgery. Further, hydrogels were loaded with bupivacaine crystals to provide sustained release beyond 72 hours in vitro. The use of crystallized bupivacaine decreased cytotoxicity compared to bupivacaine HCl. The present formulation can aid in enabling opioid-free analgesia following instrumented spinal surgery.

High efficient crosslinking of gelatin and preparation of its excellent flexible composite film using deep eutectic solvent

To overcome the gelation of gelatin at low temperatures, solve the brittleness of gelatin-based films and improve the reaction efficiency between the components, a facile design strategy is proposed for preparing gelatin/polyvinyl alcohol composite films (Gel-PVAs) with excellent flexibility. During the preparation process, sodium acetate trihydrate/urea deep eutectic solvent (SAT/U-DES) was introduced to dissolve the gelatin, which not only exhibited the higher crosslinking efficiency but also induced the plasticizing effect to the composite film. When the DES mass fraction was 60%, the solubility of the gelatin was up to 25%, and gelation did not occur at room temperature. In addition, the elongation at break of the Gel-PVA60 film reached up to 654%, which was a 631% increase when compared with that of the Gel-PVA0 film. These remarkable properties were due to the formation of new H-bonds with the groups in gelatin molecules induced by SAT/U-DES, which limited the reformation of the gelatin structures after cooling and improved the flexibility and ductility of the film. Moreover, the destruction of interchain interactions between the gelatin molecules allowed more carboxyl groups to react with PVA in the crosslinking modification system, which resulted in an improvement of the reaction efficiency without external catalysts.

Shape-Recoverable Macroporous Nanocomposite Hydrogels Created via Ice Templating Polymerization for Noncompressible Wound Hemorrhage

Uncontrolled hemorrhage resulting from severe trauma or surgical operations remains a challenge. It is highly important to develop functional materials to treat noncompressible wound bleeding. In this work, a shape-recoverable macroporous nanocomposite hydrogel was facilely created through ice templating polymerization. The covalently cross-linked gelatin networks provide a robust framework, while the Laponite nanoclay disperses into the three-dimensional matrix, enabling mechanical reinforcement and hemostatic functions. The resultant macroporous nanocomposite hydrogel possesses an inherent interconnected macroporous structure and rapid deformation recovery. In vitro assessments indicate that the hydrogel displays good cytocompatibility and a low hemolysis ratio. The hydrogel shows a higher coagulation potential and more erythrocyte adhesion compared to the commercial gauze and gelatin sponge. The noncompressible liver hemorrhage models also confirm its promising hemostasis performance. This strategy of combining a nano-enabled solution with ice templating polymerization displays great potential to develop appealing absorbable macroporous biomaterials for rapid hemostasis.

New Composite Hydrogel Based on Whey and Gelatin Crosslinked with Copper Sulphate.

By-products from the meat and dairy industries are important sources of high biological value proteins. This paper explores possibilities for improving the swelling and integrity of a cross-linked whey and gelatin hydrogel with different amounts of CuSO4 × 5H2O. Overall, swelling tests demonstrate that cross-linked samples show a better hydration capacity and stability in the hydration medium, but different copper concentrations lead to different swelling behavior. At concentrations smaller than 0.39%, the sample lasts for 75 h in a water environment before beginning to disintegrate. At a concentration of copper sulphate higher than 0.55%, the stability of the sample increased substantially. The swelling kinetics has been investigated. The diffusion constant values increased with the increase in copper concentration, but, at the highest concentration of copper (0.86%), its value has decreased. Spectroscopy analyses such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), and nuclear magnetic resonance (NMR) relaxometry analyses revealed changes in the secondary and tertiary structure of proteins as a result of the interaction of Cu2+ ions with functional groups of protein chains. In addition to its cross-linking ability, CuSO4 × 5H2O has also shown excellent antibacterial properties over common bacterial strains responsible for food spoilage. The result of this research demonstrates the potential of this hydrogel system as a unique material for food packaging.

Biomaterial Scaffolds Made of Chemically Cross-Linked Gelatin Microsphere Aggregates (C-GMSs) Promote Vascularized Bone Regeneration.

Various scaffolding systems have been attempted to facilitate vascularization in tissue engineering by optimizing biophysical properties (e.g., vascular-like structures, porous architectures, surface topographies) or loading biochemical factors (e.g., growth factors, hormones). However, vascularization during ossification remains an unmet challenge that hampers the repair of large bone defects. In this study, reconstructing vascularized bones in situ against critical-sized bone defects is endeavored using newly developed scaffolds made of chemically cross-linked gelatin microsphere aggregates (C-GMSs). The rationale of this design lies in the creation and optimization of cell-material interfaces to enhance focal adhesion, proliferation, and function of anchorage-dependent functional cells. In vitro trials are carried out by coculturing human aortic endothelial cells (HAECs) and murine osteoblast precursor cells (MC3T3-E1) within C-GMS scaffolds, in which endothelialized bone-like constructs are yielded. Angiogenesis and osteogenesis induced by C-GMSs scaffold are further confirmed via subcutaneous-embedding trials in nude mice. In situ trials for the repair of critical-sized femoral defects are subsequently performed in rats. The acellular C-GMSs with interconnected macropores, exhibit the capability to recruit the endogenous cells (e.g., bone-forming cells, vascular forming cells, immunocytes) and then promote vascularized bone regeneration as well as integration with host bone.

Dual setting brushite-gelatin cement with increased ductility and sustained drug release.

A novel dual setting brushite-gelatin cement was achieved by genip ininitiated cross-linking of gelatin during cement setting. Although the combination of an inorganic and organic phase resulted in a decrease of the compressive strength from about 10MPa without polymeric phase to 3-6-MPa for gelatin modified composites, an increase in elastic properties due to the gelatin hydrogel with a concentration of 10.0w/v% was achieved. For a powder-to-liquid ratio of 2.5g*mL-1, a shift of initial maximum stress value during compression testing was observed up to 5% deformation and tested samples showed a pseudo-ductile fracture behavior. The obtained composites of the different formulations were characterized regarding phase composition, porosity as well as drug loading capacity with rifampicin and vancomycin. For the latter, a sustained and prolonged release was realized with a drug release profile according to the Higuchi model and a release exponent of n = 0.5 for the formulation with a PLR of 2.5g*mL-1 and an incorporation of 10.0w/v% gelatin.

Biomimetic Organic-Inorganic Nanocomposite Scaffolds to Regenerate Cranial Bone Defects in a Rat Animal Model.

While bone regenerates itself after an injury, a critical bone defect requires external interventions. Engineering approaches to restore bone provide a temporary scaffold to support the damage and provide beneficial biological cues for bone repair. Biomimetically generated scaffolds replicate the naturally occurring phenomena in bone regeneration. In this study, a gelatin-calcium phosphate nanocomposite was synthesized by an efficient and cost-effective double-diffusion biomimetic approach. Calcium and phosphate ions are impregnated in the gelatin, mimicking the natural bone mineralization process. Glutaraldehyde from 0.5 to 2 w/v% was used for gelatin cross-linking and mechanical properties of the scaffold, and its biological support for rat bone marrow mesenchymal stromal cells was analyzed. Analysis of scanning electron microscopy images of the nanocomposite scaffolds and Fourier transform infrared (FTIR) and X-ray diffraction (XRD) characterizations of these scaffolds confirmed precipitation of calcium phosphates in the gelatin. Moreover, lysozyme degradation assay showed that scaffold degradation reversely correlates with the concentration of the cross-linking agent. Increased glutaraldehyde concentrations enhanced the mechanical properties of the scaffolds, bringing them closer to those of cancellous bone. Rat bone marrow mesenchymal stromal cells maintained their viability on these scaffolds compared to standard cell culture plates. In addition, these cells showed differentiation into bone lineage as evaluated from alkaline phosphatase activity up to 21 days and Alizarin red staining of the cells over 28 days. Eventually, scaffolds were implanted in a cranial defect in a rat animal model with a 5 mm diameter. Bone regeneration was studied over 90 days. Analysis of histological sections of the injury and computer tomography images revealed that nanocomposite scaffolds cross-linked with 1% w/v glutaraldehyde provide the maximum bone regeneration after 90 days. Collectively, our data show that nanocomposite scaffolds developed here provide effective regeneration for extensive bone defects in vivo.

Development of a food grade sanitizer delivery system with chlorine loaded gelatin microgels for enhanced binding and inactivation of biofilms

Sanitation of water, food, and food contact surfaces is essential for the safety of food supply. Lack of stability of sanitizers in the presence of organic content and lack of targeted binding of sanitizers to biofilms can reduce effectiveness of sanitizers and increase the risk of contamination of food. Therefore, this study evaluated the development, characterization, and application of gelatin microgel based chlorine delivery system for improving both stability of chlorine based sanitizer and targeted binding of sanitizer to biofilms. The results illustrate that cross-linked gelatin microgels rapidly bind chlorine to form a halamine bond. The total chlorine loading was 5.05% per gram of gelatin microgels. Chlorine bound to gelatin microgels was stable in the presence of high organic content up to 2,000 mg/L and in a powder form for 5 weeks under refrigerated conditions. Gelatin microgel particles significantly improve the inactivation of bacteria in the presence of organic content compared to equivalent concentration of free chlorine. Gelatin microgel particles had affinity to bind biofilms with 26.5% and 22.9% to the L. innocua and E. coli O157:H7 biofilms, respectively. In bacterial biofilm models, more than 6 log CFU/cm2 of L. innocua and E. coli O157:H7 were inactivated within 60 min using chlorine charged gelatin microgel particles while equivalent free chlorine could only achieve 4 log CFU/cm2 inactivation during the same period. Overall, the results demonstrate potential of protein microgels for effective binding and delivery of chlorine to improve sanitation of wash water with suspended organics and food contact surfaces.

Development of carboxymethyl cellulose/gelatin hybrid hydrogels via radiation-induced cross-linking as novel anti-adhesion barriers

Adhesion after abdominal and pelvic surgery results in severe clinical outcomes and a negative impact on the quality of life of a patient. Implanting barrier materials is a common strategy for preventing postoperative adhesion, and non-adhesive carboxymethylcellulose (CMC) is a widely used material for such purpose. Herein, we present CMC/gelatin (CMC/G) hybrid hydrogels as novel barrier materials that aim to reduce the foreign body response (FBR) by combining the biocompatibility and biodegradability of gelatin and the non-adhesiveness of CMC and by realizing mechanical matching with the host tissue. The hydrogels were prepared by the simple reagent-free γ-ray irradiation-induced cross-linking of CMC and gelatin. The hydrogel composition was controlled by varying the initial mixing ratio. The gelatin fraction provided enzyme-mediated degradability at a content ≥ 40%, and the degradation rate was controlled by the radiation dose. The compressive moduli of the hydrogels were tuned to be identical to that of target abdominal organs (several tens of kPa) via 10–30 kGy radiation. The hydrogels sufficiently prevented adhesion of 3T3-Swiss fibroblast cells owing to the non-adhesive capability of CMC which surpassed the high cell adhesiveness of gelatin in the hydrogels. On the other hand, the added gelatin significantly improved the viability of the few cells that adhered to the hydrogels. We found that hydrogels composed of 60% CMC and 40% gelatin exhibited significantly higher cell viabilities while maintaining the non-adhesiveness which is desirable as barrier materials. The in vitro assessments demonstrated the potential of the hydrogel as a novel barrier material with excellent biocompatibility, wound healing promoting effect, and FBR reducing effect by realizing mechanical matching with the host abdominal organs, especially when it was composed of 60% CMC and 40% gelatin and cross-linked at 10–30 kGy to impart compressive modulus of 20–100 kPa.

Catalytic Reduction of Environmental Pollutants with Biopolymer Hydrogel Cross-Linked Gelatin Conjugated Tin-Doped Gadolinium Oxide Nanocomposites.

In the present study, a biopolymer nanocomposite hydrogel based on gelatin and tin-doped gadolinium oxide (Sn-Gd2O3@GH) was prepared for the efficient reduction of water pollutants. The method of Sn-Gd2O3@GH preparation consisted of two steps. A Sn-Gd2O3 nanomaterial was synthesized by a hydrothermal method and mixed with a hot aqueous solution (T > 60 °C) of gelatin polymer, followed by cross-linking. Due to the presence of abundant functional groups on the skeleton of gelatin, such as carboxylic acid (–COOH) and hydroxyl (–OH), it was easily cross-linked with formaldehyde. The structure, morphology, and composition of Sn-Gd2O3@GH were further characterized by the FESEM, XRD, EDX, and FTIR techniques. The FESEM images located the distribution of the Sn-Gd2O3 nanomaterial in a GH matrix of 30.06 nm. The XRD patterns confirmed the cubic crystalline structure of Gd2O3 in a nanocomposite hydrogel, while EDS elucidated the elemental composition of pure Sn-Gd2O3 powder and cross-linked the Sn-Gd2O3@GH samples. The synthesized Sn-Gd2O3@GH nanocomposite was used for the removal of different azo dyes and nitrophenols (NPs). It exhibited an efficient catalytic reduction of Congo red (CR) with a reaction rate of 9.15 × 10−1 min−1 with a strong NaBH4-reducing agent. Moreover, the Sn-Gd2O3@GH could be easily recovered by discharging the reduced (colourless) dye, and it could be reused for a fresh cycle.

Cross-Linked Gelatine by Modified Dextran as a Potential Bioink Prepared by a Simple and Non-Toxic Process.

Essential features of well-designed materials intended for 3D bioprinting via microextrusion are the appropriate rheological behavior and cell-friendly environment. Despite the rapid development, few materials are utilizable as bioinks. The aim of our work was to design a novel cytocompatible material facilitating extrusion-based 3D printing while maintaining a relatively simple and straightforward preparation process without the need for harsh chemicals or radiation. Specifically, hydrogels were prepared from gelatines coming from three sources—bovine, rabbit, and chicken—cross-linked by dextran polyaldehyde. The influence of dextran concentration on the properties of hydrogels was studied. Rheological measurements not only confirmed the strong shear-thinning behavior of prepared inks but were also used for capturing cross-linking reaction kinetics and demonstrated quick achievement of gelation point (in most cases < 3 min). Their viscoelastic properties allowed satisfactory extrusion, forming a self-supported multi-layered uniformly porous structure. All gelatin-based hydrogels were non-cytototoxic. Homogeneous cells distribution within the printed scaffold was confirmed by fluorescence confocal microscopy. In addition, no disruption of cells structure was observed. The results demonstrate the great potential of the presented hydrogels for applications related to 3D bioprinting.

Bio-based poly (γ-glutamic acid)-gelatin double-network hydrogel with high strength for wound healing

Building bio-based hydrogels with high strength and biocompatibility is still a challenge. Herein, we successfully constructed a hybrid double-network (DN) full biological hydrogel with excellent mechanical properties and biocompatibility by introducing a physically cross-linked gelatin (GEL) network in a covalently cross-linked poly (γ-glutamic acid) (γ-PGA) network. The γ-PGA-GEL DN hydrogel demonstrated ultra-high compression performance (38 MPa), which was better than all currently reported γ-PGA-based hydrogels, and its tensile performance (0.27 MPa) was also satisfactory. Due to the unique multi-crosslinked DN structure, the γ-PGA-GEL DN hydrogel had better recovery and healing properties than those of the γ-PGA single-network (SN) hydrogel. In addition, the γ-PGA-GEL DN hydrogel exhibited good transparency, swelling and degradability. In vitro cell experiments demonstrated that the γ-PGA-GEL DN hydrogel was beneficial to cell adhesion and proliferation. The evaluation of the full-thickness skin defects model in rats exhibited that the γ-PGA-GEL DN hydrogel could significantly accelerate wound healing. These results indicated that the γ-PGA-GEL DN hydrogel was an ideal candidate material for wound dressing.

An injectable hydroxypropyl-β-cyclodextrin cross-linked gelatin-based hydrogel loaded bone mesenchymal stem cell for osteogenic and in vivo bone regeneration of femoral head necrosis

An injectable hydroxypropyl-β-cyclodextrin (HPβCD) cross-linking of gelatin (Gel) based hydrogel was embedded with BMSC in vivo bone regeneration of femoral head necrosis. This HPβCD-Gel hydrogel possesses quick gelation within 6 min; a high-water uptake resulted in faster biodegradation, high swelling, and a 3D porous network that strengthened its mechanical, surface, and morphological properties. The results indicated that BMSC showed high cell viability (>90%) during measurement; HPβCD-Gel hydrogels induced BMSC differentiation into osteocytes within 14 days more efficiently than the osteogenic medium. The HPβCD-Gel/BMSC hydrogels that were injected into the necrosis site of the femoral head in the vessels were measured for 2 weeks. In addition, the vessel density and mean vessel diameters increased in the next 2-8 weeks followed by increased new bone formation, according to the in vivo analysis. Overall, our findings show that this method is a promising strategy for improving femoral head necrosis bone regeneration.

Folic acid-modified photoluminescent dialdehyde carboxymethyl cellulose crosslinked bionanogels for pH-controlled and tumor-targeted co-drug delivery

This work aimed to fabricate a new photoluminescent bionanogel with both targeted anticancer drug delivery and bioimaging potentials. Briefly, at first photoluminescent carbon dots (CDs) were synthesized from the low-cost and more available black pepper with traditional medicinal properties. The as-synthesized dialdehyde carboxymethyl cellulose (DCMC) was used as a safe crosslinker for gelatin crosslinking in the presence of CDs (CDs/DCMC-Gel). Eventually, the residual amine functional groups of gelatin were used for the conjugation of CDs/DCMC-Gel with folic acid (FA) ((CDs/DCMC-Gel)-FA bionanogels). All employed physicochemical characterization methods approved the (CDs/DCMC-Gel)-FA bionanogels fabrication route. SEM analysis specified the spherical morphology with a diameter of ~70–90 nm for it. Curcumin (CUR) and doxorubicin (DOX) respectively were loaded with drug entrapment efficiency of about 44.0% and 41.4%. The release rate for both drugs in acidic conditions was higher than in physiological conditions. In vitro antitumor experiments; MTT, DAPI staining, cellular uptake, and cell cycle tests showed the superior anticancer effect of the CUR@DOX@(CDs/DCMC-Gel)-FA in comparison with free CUR@DOX. Moreover, the (CDs/DCMC-Gel)-FA acted as a hopeful bio-imaging tool. Taken together, the designed (CDs/DCMC-Gel)-FA could be proposed as a promising nanosystem for efficient chemotherapy.

A paper microfluidic device based colorimetric sensor for the detection and discrimination of elapid versus viper envenomation.

Snake bites are a neglected tropical disease, causing mortality and severe damage to various vital organs like the nervous system, kidneys and heart. There is increasing interest in designing new antivenom treatments that are more specific to particular groups (either taxonomic or regional) of species, given the increasing evidence that current polyvalent Indian antivenom is ineffective in many situations. Under these circumstances, being able to detect the species, or a group of species, responsible for the envenomation becomes important. Unfortunately, no such diagnostic tool is available in the Indian market. Such a tool will need to be rapid, sensitive and affordable. To address this need, we have combined the power of nanotechnology and paper microfluidics and herein report a device that has the ability to detect and differentiate viper venom from elapid and scorpion venom. In principle, this assay is based on the release of the dye from the stimuli-responsive glutaraldehyde cross-linked methylene blue-loaded gelatin (GMG) nanoparticles in the presence of snake venom metalloproteases and serine proteases. The developed equipment-free assay can detect and discriminate viper venom from that of elapids and scorpions. The low-end detection limit of the sensor is ∼3.0 ng for the saw-scaled viper Echis carinatus, while the same for Russell's viper Daboia russelii is ∼6.0 ng. The performance of the sensor remains unaltered for different batches of GMG nanoparticles. Altogether, this finding establishes the role of nanotechnology and paper microfluidics in the rapid and accurate detection of viper venom.

Mechanochromic luminescence of a bionanocomposite hydrogel.

Bionanocomposite hydrogels were prepared from gelatin hydrogel and subsequent ionic crosslinking in the presence of a smectite with adsorbed cyanine dye (pseudoisocyanine). In addition to the improved mechanical properties achieved by the hybridization with the smectite, the composite hydrogel underwent a photoluminescence color change from red to blue upon stretching and recovered from blue to red upon relaxing. The novel luminescence mechanochromism was explained by the aggregation/de-aggregation of the cyanine dye adsorbed on the smectite by stretching/relaxing.